Hydraulic fluid couplings are used to connect hydraulic hoses as part of hydraulic fluid power systems on both mobile and stationary power equipment. In instances where the hoses are attached to equipment components that move or twist relative to one another, the coupling must accommodate torsional movement to prevent binding and/or kinking of the hoses. An inline swivel joint is normally employed in these situations.
Prior art hydraulic fluid couplings comprising inline swivel joints have suffered from the problem that, when loaded with internal hydraulic fluid pressure, the swivel becomes difficult to turn. This leads to binding and kinking of the hoses and ultimately hose or coupling failure. The prior art couplings are also prone to excessive bearing wear due to the high loads imparted to the bearings by fluid pressure; this leads to premature bearing failure with the result that the swivel becomes more difficult to turn, exacerbating the hose twisting problem.
As a result, there remains a need for an improved hydraulic fluid coupling, particularly a hydraulic fluid coupling comprising an inline swivel joint. Such a coupling would desirably be easy to turn and not be prone to premature bearing failure.